The present invention relates to a rocket engine using a liquid fuel, and more particularly to an improvement in the fuel system for use in a rocket engine wherein a pressure drop of a chemical liquid fuel is minimized to ensure a stable supply of power for a gasified fuel pressure booster of a rocket engine.
In the art of rocket engine, there is generally known a liquid fuel rocket engine of expander cycle type. Now, reference is made to a typical basic construction of this type rocket engine as shown in FIG. 2, which is constructed such that a propellant 1, for example, liquid hydrogen is pressurized to a desired pressure level by means of a fuel pressure booster 3, which is a fuel pump, and wherein a second propellant 2, for example, liquid oxygen which is an oxidizing agent reacting with the first propellant 1 to be deflagrated together is pressurized to a certain desired pressure by means of another pressure booster 4 for an oxidizing agent, which is an oxidizer pump. With this construction, thus-boosted propellant (liquid oxygen) 2 is then directed to a combustor 6. On the other hand, it is also constructed that thus-boosted propellant (liquid hydrogen) 1 is directed through a combustor cooling jacket 7 as arranged extensively around the combustor 6 so as to cool-off the same, and then is redirected to a booster driving unit 5 such as a gas turbine and the like mechanism, which is driven in rotation with this propellant, from which it is further directed to the combustor 6. In this combustor 6, the propellants 1 and 2 react with each other to be combusted or deflagrated together to produce a high pressure gas stream, which is to be released outwardly through an expansion nozzle 8 so as to generate a great propulsive force of a rocket engine.
The propellant 1 boosted in pressure by means of the fuel booster 3 gains a temperature rise while cooling-off the combustor 6, also having a concurrent pressure rise. With thus-gained pressure of the propellant 1, the booster driving unit 5 is driven in rotation, accordingly.
The driving power from the booster driving unit 5 is adapted to drive each of the fuel and oxidizer boosters 3 and 4 in rotating motion by way of a gear transmission 10.
According to the conventional rocket engine construction wherein the propellant 1 gaining heat from part of the heat as generated from the combustor 6 is adapted to be a driving medium for the fuel and oxidizer boosters 3 and 4, it has generally been arranged such that the whole quantity of the propellant 1 with heat gains is directed to use as the driving fluid for the both boosters 3 and 4.
Also, it is the common practice in the conventional arrangement of a rocket engine that heat as generated from the combustor 6 is absorbed by cooling the same with the liquid phase propellant, and this is the so-called regeneration-cooling system. In such arrangement that the whole quantity of the propellant 1 which is once used for the purpose of cooling of the combustor is adapted as the driving medium for the fuel and oxidizer boosters 3 and 4, however, it is essentially required that the fuel booster 3 for that propellant 1 should be designed with a substantial capacity which is large enough to compensate for a loss in pressure as generated while passing through the combustor cooling jacket 7, plus an inevitable pressure drop as encountered in the driving of the booster driving unit 5, and so it is consequently required to employ a large capacity booster unit to counter such losses in pressures, accordingly.
In coping with such undesirable problems, there is proposed a countermeasure in design as typically shown in FIG. 3 such that a subcombustor 11 which is adapted as a drive source for the fuel booster 3 to introduce part of the propellants 1 and 2 thereinto so as to be combusted therein and have thus-produced combustion gas made available for energizing the fuel booster, which is of the so-called gas generation cycle system. With such a construction, however, it brings such drawback that the entire system may inevitably turn out to be complex in construction, and thus resulting in a substantial increase in weight and hence reduction in the reliability of the system. In this arrangement as shown in FIG. 3, there is seen provided an expansion nozzle cooling jacket designated at the reference number 9 defined extensively around a high-expansion nozzle 8 and adapted to pass a coolant therethrough in such a manner that part of the propellant 1 from the combustor cooling jacket 7 is introduced as a coolant for the high expansion nozzle 8 through the expansion nozzle cooling jacket 9, and that propellant is then discharged outwardly to the atmosphere.
Also, a system has been known in which, as shown in FIG. 4, the subcombustor 11 is eliminated and a lower end outlet of the high expansion nozzle cooling jacket 9 is connected to the booster driving unit 5 so that the thermal energy the propellant 1 coming out of the cooling jacket 9 is used in the driving units (this system will be called a "down pass system" hereinafter).
The present invention is essentially directed to the provision of a due and proper resolution to such inconveniences and difficulties in practice as outlined above and experienced in the conventional liquid fuel booster for a rocket engine which has heretofore been left unattended with any proper countermeasures therefor.